Story summary.MAXO is short for "microwave artifact of xenobiological origin" - a kind of radio signals received on earth where the signals are of alien origin.

Story doesn't specify the year it happens. At the time of narration, at least 21 MAXO signals have been received - all from nearby star systems. Many talented individuals have spent a lot of time decoding them.

Decoding turns out to be simpler than expected. And out pops a very familiar message!